1. Field of the Invention
The present invention relates to an apparatus for continuously molding cylindrical blocks of foamed polymeric material, and more particularly, foamed polyurethane blocks for subsequent conversion into sheeting by a process of peeling.
2. Description of the Prior Art
It is known to produce sheets of foamed polyurethane for use as carpet backing, laminate lining in clothing, etc., by first producing blocks of foamed polyurethane in cylindrical shape and then peeling a sheet from the cylindrical blocks, thus reducing waste. The foamed polyurethane blocks are formed by depositing liquid foam reactants on an inclined conveying surface and gradually forming the cylinder as the foam is allowed to rise freely by means of a conveyor made up of arcuate mold sections moving along with the conveyor. Examples of such apparatuses and processes are found in U.S. Pat. Nos. 3,281,894, issued Nov. 1, 1966 to Fred Buff et al; 3,296,658, issued Jan. 10, 1967, also to Fred Buff et al; 3,726,623, issued Apr. 10, 1973 to C. Ferstenberg; 3,729,534, issued Apr. 24, 1973, also to C. Ferstenberg; and 3,840,629, issued Oct. 8, 1974 to J. E. Marjoram.
Because of the unusual length required to mold large polyurethane blocks, it is of advantage to find a way to reduce the amount of molding length that is required to form such large diameter blocks. A good discussion of the problems of the dimensions involved is found in U.S. Pat. No. 3,786,122, issued Jan. 15, 1974 to L. Berg. His solution in relation to reducing the length of the conveyor and to overcoming the need for complicated feed head arrangements is discussed in this patent as well as in his U.S. Pat. No. 3,832,099, issued Aug. 27, 1974. In both these patents, Berg suggests providing an upright molding trough at the leading edge of the conveyor. The trough is of rectangular cross-section, and a weir structure is provided in which an initial rectangular shape is given to the expanding foam polyurethane as it flows onto the conveyor. U.S. Pat. No. 4,093,109, issued June 6, 1978 to M. J. Schrader, is also directed to such an apparatus.
It would be of advantage to be able to apply the trough of Berg to the apparatus for forming blocks of cylindrical shape as described in the aforementioned patents. However, the preforming trough of Berg is by its very shape suitable for forming rectangular blocks.